Handwritten notes in which the police officer who led the hunt for Jack The Ripper names his chief suspect for the gruesome murders were donated to Scotland Yard yesterday.
The notes are contained within a book handed down through the family of Chief Inspector Donald Swanson, which was formally presented to the Metropolitan Police to mark the re-launch of its world-famous crime museum.
In his annotations, Mr Swanson names Polish barber Aaron Kosminski as the suspect in the notorious Ripper case.
He had made his handwritten notes in a book called The Lighter Side of my Official Life, the memoirs of Dr Robert Anderson, who was Scotland Yard's assistant commissioner at the time of the Ripper investigation.
Mr Swanson made his personal notes in the margin, naming Kosminski and explaining why he believed him to be the killer who stalked east London back in 1888, claiming the lives of at least five women.
The book, which was passed to Mr Swanson's daughter and then his nephew, was formally presented to the Metropolitan Police by the officer's relatives, including his great-grandson Nevill Swanson.
The presentation marks the re-launch of the force's crime museum, the oldest museum of its kind in the world.
Mr Swanson's notes, which have been public knowledge since the 1980s, provide one of the best clues to the Ripper's real identity but they do not solve the case conclusively.
Kosminski was named as a suspect in a famous
memorandum by Assistant Chief Constable Sir Melville MacNaghten, written back in 1894.
Kosminski came to the attention of police after threatening his sister with a knife.
Although he was soon identified as a possible suspect in the Ripper investigation, he was insane so detectives could not interview him.
Instead he was taken to the Metropolitan Police convalescent home in Brighton where he was put through an identity parade. The only alleged witness to any of the Ripper murders picked him out.
The witness was said to have been Jewish, like Kosminski, and refused to testify against a fellow Jew for a crime for which, if he had been found guilty, he could have been executed.
Kosminski ended up in a workhouse in Stepney, east London, and then an asylum in Colney Hatch. He died in 1919.
As there is no surviving forensic evidence from the case, it is impossible for detectives to prove the identity of Jack The Ripper.
But Detective Chief Super-intendent Steve Lovelock said Mr Swanson's evidence, which is known as "the Swanson Marginalia", carried considerable weight.
"For that person (Swanson) to be compelled in his own handwriting to name the suspect is something of some significance," he said.
Mr Lovelock said he could not explain why Kosminski's name had never been made public at the time of the Ripper murders.
Mr Swanson's notes read: "After the suspect had been identified at the seaside home where he had been sent by us with difficulty in order to subject him to identification, and he knew he was identified.
"On suspect's return to his brother's house in Whitechapel he was watched by police (City CID) by day and night.
"In a very short time the suspect with his hands tied behind his back, he was sent to Stepney Workhouse and then to Colney Hatch and died shortly afterwards - Kosminski was the suspect - DSS."